High shear process for the production of chlorobenzene

ABSTRACT

Use of a high shear mechanical device incorporated into a process for the production of chlorobenzene is capable of decreasing mass transfer limitations, thereby enhancing the chlorobenzene production process. A system for the production of chlorobenzene from benzene and chlorine, the system comprising a reactor and an external high shear device, the outlet of which is fluidly connected to the inlet of the reactor; the high shear device capable of providing a emulsion of chlorine gas bubbles within liquid benzene

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. § 119(e) of U.S.Provisional Patent Application No. 60/946,524 filed Jun. 27, 2007, thedisclosure of which is hereby incorporated herein by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable.

BACKGROUND OF THE INVENTION

1. Technical Field

The present disclosure relates generally to the production ofchlorobenzene by chlorination of benzene and, more particularly, toapparatus and methods for producing chlorobenzene via chlorination ofbenzene in a high shear process. More specifically, the disclosurepertains still more particularly to the reduction of mass transferlimitations for converting benzene to chlorobenzene.

2. Background of the Invention

Chlorobenzene is used as a solvent with applications in certainpesticide formulations, automotive and industrial degreasers, and as achemical intermediate to make herbicides, rubber, and dyes. Benzenereacts with chlorine in the presence of a catalyst at room temperature,replacing one of the hydrogen atoms on the benzene ring with a chlorineatom. The catalyst is typically aluminum chloride or iron.

Iron is altered during the reaction such that chlorine forms iron (III)chloride, FeCl₃.

2Fe+3Cl₂→2FeCl₃  (1)

This compound acts as the catalyst and behaves like aluminum chloride,AlCl₃, in the reaction. The reaction between benzene and chlorine in thepresence of either aluminum chloride or iron gives chlorobenzene, or,written more compactly:

C₆H₆+Cl₂→C₆H₅Cl+HCl.  (2)

C₆H₅+Cl₂→C₆H₄Cl+HCl.  (3)

C₆H₅Cl₂+Cl₂→C₆H₃Cl+HCl.  (4)

As reaction (2) is the desired reaction, certain parameters must bemaintained in the reactor. In certain cases, dichlorobenzene can beformed if reaction temperatures are not controlled properly.

There is a need in the industry for improved methods of producingchlorobenzene from benzene and chlorine whereby costs may be reduced viaoperation at lower temperature and/or pressure, increased product yield,decreased reaction time, and/or reduced capital and/or operating costs.

SUMMARY OF THE INVENTION

A high shear system and method for accelerating the production ofchlorobenzene is disclosed. The disclosed high shear method reduces masstransfer limitations, thereby improving reaction conditions in thereactor such as the reaction rate, temperature, pressure, contact time,and/or product yield. In accordance with certain embodiments of thepresent disclosure, a method is provided that enhances the rate of aliquid phase process for the production of chlorobenzene from benzene byproviding for more optimal time, temperature, and pressure conditionsthan are currently used.

The method employs a high shear mechanical device to provide enhancedtime, temperature, and pressure conditions resulting in acceleratedchemical reactions between multiphase reactants.

In an embodiment, the method comprises the use of a pressurized highshear device to provide for production of chlorobenzene without the needfor large volume reactors.

These and other embodiments, features, and advantages will be apparentin the following detailed description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more detailed description of the preferred embodiment of thepresent invention, reference will now be made to the accompanyingdrawings, wherein:

FIG. 1 is a cross-sectional diagram of a high shear device for theproduction of chlorobenzene.

FIG. 2 is a process flow diagram according to an embodiment of thepresent disclosure including a high shear device for production ofchlorobenzene.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Overview

A system and method employs an external high shear mechanical device toprovide rapid contact and mixing of chemical ingredients in a controlledenvironment in the reactor/mixer device. The high shear device reducesthe mass transfer limitations on the reaction and thus increases theoverall reaction rate.

Chemical reactions involving liquids, gases and solids rely on the lawsof kinetics that involve time, temperature, and pressure to define therate of reactions. In cases where it is desirable to react two or moreraw materials of different phases (e.g. solid and liquid; liquid andgas; solid, liquid and gas), one of the limiting factors in controllingthe rate of reaction involves the contact time of the reactants. In thecase of heterogeneously catalyzed reactions there may be the additionalrate limiting factor of having the reaction products removed from thesurface of the catalyst to enable the catalyst to catalyze furtherreactants.

In conventional reactors, contact time for the reactants and/or catalystis often controlled by mixing which provides contact between two or morereactants involved in a chemical reaction. A reactor assembly thatcomprises an external high shear mixer makes possible decreased masstransfer limitations and thereby allows the reaction to more closelyapproach kinetic limitations. When reaction rates are accelerated,residence times may be decreased, thereby increasing obtainablethroughput. Alternatively, where the current yield is acceptable,decreasing the required residence time allows for the use of lowertemperatures and/or pressures than conventional processes.

High Shear Device

High shear devices (HSD) such as a high shear mixer, or high shear mill,are generally divided into classes based upon their ability to mixfluids. Mixing is the process of reducing the size of inhomogeneousspecies or particles within the fluid. One metric for the degree orthoroughness of mixing is the energy density per unit volume that themixing device generates to disrupt the fluid particles. The classes aredistinguished based on delivered energy density. There are three classesof industrial mixers having sufficient energy density to consistentlyproduce mixtures or emulsions with particle or bubble sizes in the rangeof 0 to 50 μm.

Homogenization valve systems are typically classified as high energydevices. Fluid to be processed is pumped under very high pressurethrough a narrow-gap valve into a lower pressure environment. Thepressure gradients across the valve and the resulting turbulence andcavitations act to break-up any particles in the fluid. These valvesystems are most commonly used in milk homogenization and can yieldaverage particle size range from about 0.01 μm to about 1 μm. At theother end of the spectrum are high shear mixer systems classified as lowenergy devices. These systems usually have paddles or fluid rotors thatturn at high speed in a reservoir of fluid to be processed, which inmany of the more common applications is a food product. These systemsare usually used when average particle, globule or bubble, sizes ofgreater than 20 microns are acceptable in the processed fluid.

Between low energy—high shear mixers and homogenization valve systems,in terms of the mixing energy density delivered to the fluid, arecolloid mills, which are classified as intermediate energy devices. Thetypical colloid mill configuration includes a conical or disk rotor thatis separated from a complementary, liquid-cooled stator by aclosely-controlled rotor-stator gap, which is maybe between 0.025 mm and10.0 mm. Rotors are usually driven by an electric motor through a directdrive or belt mechanism. Many colloid mills, with proper adjustment, canachieve average particle, or bubble, sizes of about 0.01 μm to about 25μm in the processed fluid. These capabilities render colloid millsappropriate for a variety of applications including colloid andoil/water-based emulsion processing such as that required for cosmetics,mayonnaise, silicone/silver amalgam formation, or roofing-tar mixing.

Referring now to FIG. 1, there is presented a schematic diagram of ahigh shear device 200. High shear device 200 comprises at least onerotor-stator combination. The rotor-stator combinations may also beknown as generators 220, 230, 240 or stages without limitation. The highshear device 200 comprises at least two generators, and most preferably,the high shear device comprises at least three generators.

The first generator 220 comprises rotor 222 and stator 227. The secondgenerator 230 comprises rotor 223, and stator 228; the third generatorcomprises rotor 224 and stator 229. For each generator 220, 230, 240 therotor is rotatably driven by input 250. The generators 220, 230, 240rotate about axis 260 in rotational direction 265. Stator 227 is fixablycoupled to the high shear device wall 255.

The generators include gaps between the rotor and the stator. The firstgenerator 220 comprises a first gap 225; the second generator 230comprises a second gap 235; and the third generator 240 comprises athird gap 245. The gaps 225, 235, 245 are between about 0.025 mm (0.01in) and 10.0 mm (0.4 in) wide. Alternatively, the process comprisesutilization of a high shear device 200 wherein the gaps 225, 235, 245are between about 0.5 mm (0.02 in) and about 2.5 mm (0.1 in). In certaininstances the gap is maintained at about 1.5 mm (0.06 in).Alternatively, the gaps 225, 235, 245 are different between generators220, 230, 240. In certain instances, the gap 225 for the first generator220 is greater than about the gap 235 for the second generator 230,which is greater than about the gap 245 for the third generator 240.

Additionally, the width of the gaps 225, 235, 245 may comprise a coarse,medium, fine, and super-fine characterization. Rotors 222, 223, and 224and stators 227, 228, and 229 may be toothed designs. Each generator maycomprise two or more sets of rotor-stator teeth, as known in the art.Rotors 222, 223, and 224 may comprise a number of rotor teethcircumferentially spaced about the circumference of each rotor. Stators227, 228, and 229 may comprise a number of stator teethcircumferentially spaced about the circumference of each stator. Inembodiments, the inner diameter of the rotor is about 11.8 cm. Inembodiments, the outer diameter of the stator is about 15.4 cm. Infurther embodiments, the rotor and stator may have an outer diameter ofabout 60 mm for the rotor, and about 64 mm for the stator.Alternatively, the rotor and stator may have alternate diameters inorder to alter the tip speed and shear pressures. In certainembodiments, each of three stages is operated with a super-finegenerator, comprising a gap of between about 0.025 mm and about 3 mm.When a feed stream 205 including solid particles is to be sent throughhigh shear device 200, the appropriate gap width is first selected foran appropriate reduction in particle size and increase in particlesurface area. In embodiments, this is beneficial for increasing catalystsurface area by shearing and dispersing the particles.

High shear device 200 is fed a reaction mixture comprising the feedstream 205. Feed stream 205 comprises an emulsion of the dispersiblephase and the continuous phase. Emulsion refers to a liquefied mixturethat contains two distinguishable substances (or phases) that will notreadily mix and dissolve together. Most emulsions have a continuousphase (or matrix), which holds therein discontinuous droplets, bubbles,and/or particles of the other phase or substance. Emulsions may behighly viscous, such as slurries or pastes, or may be foams, with tinygas bubbles suspended in a liquid. As used herein, the term “emulsion”encompasses continuous phases comprising gas bubbles, continuous phasescomprising particles (e.g., solid catalyst), continuous phasescomprising droplets of a fluid that is substantially insoluble in thecontinuous phase, and combinations thereof.

Feed stream 205 may include a particulate solid catalyst component. Feedstream 205 is pumped through the generators 220, 230, 240, such thatproduct dispersion 210 is formed. In each generator, the rotors 222,223, 224 rotate at high speed relative to the fixed stators 227, 228,229. The rotation of the rotors pumps fluid, such as the feed stream205, between the outer surface of the rotor 222 and the inner surface ofthe stator 227 creating a localized high shear condition. The gaps 225,235, 245 generate high shear forces that process the feed stream 205.The high shear forces between the rotor and stator functions to processthe feed stream 205 to create the product dispersion 210. Each generator220, 230, 240 of the high shear device 200 has interchangeablerotor-stator combinations for producing a narrow distribution of thedesired bubble size, if feedstream 205 comprises a gas, or globule size,if feedstream 205 comprises a liquid, in the product dispersion 210.

The product dispersion 210 of gas particles, or bubbles, in a liquidcomprises an emulsion. In embodiments, the product dispersion 210 maycomprise a dispersion of a previously immiscible or insoluble gas,liquid or solid into the continuous phase. The product dispersion 210has an average gas particle, or bubble, size less than about 1.5 μm;preferably the bubbles are sub-micron in diameter. In certain instances,the average bubble size is in the range from about 1.0 μm to about 0.1μm. Alternatively, the average bubble size is less than about 400 nm(0.4 μm) and most preferably less than about 100 nm (0.1 μm).

Tip speed is the velocity (m/sec) associated with the end of one or morerevolving elements that is transmitting energy to the reactants. Tipspeed, for a rotating element, is the circumferential distance traveledby the tip of the rotor per unit of time, and is generally defined bythe equation V (m/sec)=π·D·n, where V is the tip speed, D is thediameter of the rotor, in meters, and n is the rotational speed of therotor, in revolutions per second. Tip speed is thus a function of therotor diameter and the rotation rate.

For colloid mills, typical tip speeds are in excess of 23 m/sec (4500ft/min) and can exceed 40 m/sec (7900 ft/min). For the purpose of thepresent disclosure the term ‘high shear’ refers to mechanicalrotor-stator devices, such as mills or mixers, that are capable of tipspeeds in excess of 5 m/sec (1000 ft/min) and require an externalmechanically driven power device to drive energy into the stream ofproducts to be reacted. A high shear device combines high tip speedswith a very small shear gap to produce significant friction on thematerial being processed. Accordingly, a local pressure in the range ofabout 1000 MPa (about 145,000 psi) to about 1050 MPa (152,300 psi) andelevated temperatures at the tip of the shear mixer are produced duringoperation. In certain embodiments, the local pressure is at least about1034 MPa (about 150,000 psi). The local pressure further depends on thetip speed, fluid viscosity, and the rotor-stator gap during operation.

An approximation of energy input into the fluid (kW/l/min) can be madeby measuring the motor energy (kW) and fluid output (1/min). Inembodiments, the energy expenditure of a high shear device is greaterthan 1000 W/m³. In embodiments, the energy expenditure is in the rangeof from about 3000 W/m³ to about 7500 W/m³. The high shear device 200combines high tip speeds with a very small shear gap to producesignificant shear on the material. The amount of shear is typicallydependent on the viscosity of the fluid. The shear rate generated in ahigh shear device 200 may be greater than 20,000 s⁻¹. In embodiments,the shear rate generated is in the range of from 20,000 s⁻¹ to 100,000s⁻¹.

The high shear device 200 produces a gas emulsion capable of remainingdispersed at atmospheric pressure for at least about 15 minutes. For thepurpose of this disclosure, an emulsion of gas particles, or bubbles, inthe dispersed phase in product dispersion 210 that are less than 1.5 μmin diameter may comprise a micro-foam. Not to be limited by a specifictheory, it is known in emulsion chemistry that sub-micron particles, orbubbles, dispersed in a liquid undergo movement primarily throughBrownian motion effects. The bubbles in the emulsion of productdispersion 210 created by the high shear device 200 may have greatermobility through boundary layers of solid catalyst particles, therebyfacilitating and accelerating the catalytic reaction through enhancedtransport of reactants.

The rotor is set to rotate at a speed commensurate with the diameter ofthe rotor and the desired tip speed as described hereinabove. Transportresistance is reduced by incorporation of high shear device 200 suchthat the velocity of the reaction is increased by at least about 5%.Alternatively, the high shear device 200 comprises a high shear colloidmill that serves as an accelerated rate reactor. The accelerated ratereactor comprises a single stage dispersing chamber. The acceleratedrate reactor comprises a multiple stage inline disperser comprising atleast 2 stages.

Selection of the high shear device 200 is dependent on throughputrequirements and desired particle or bubble size in the outletdispersion 210. In certain instances, high shear device 200 comprises aDispax Reactor® of IKA® Works, Inc. Wilmington, N.C. and APV NorthAmerica, Inc. Wilmington, Mass. Model DR 2000/4, for example, comprisesa belt drive, 4M generator, PTFE sealing ring, inlet flange 1″ sanitaryclamp, outlet flange ¾″ sanitary clamp, 2HP power, output speed of 7900rpm, flow capacity (water) approximately 300 l/h to approximately 700l/h (depending on generator), a tip speed of from 9.4 m/s to about 41m/s (about 1850 ft/min to about 8070 ft/min). Several alternative modelsare available having various inlet/outlet connections, horsepower, tipspeeds, output rpm, and flow rate.

Without wishing to be limited to a particular theory, it is believedthat the level or degree of high shear mixing is sufficient to increaserates of mass transfer and may also produce localized non-idealconditions that enable reactions to occur that would not otherwise beexpected to occur based on Gibbs free energy predictions. Localized nonideal conditions are believed to occur within the high shear deviceresulting in increased temperatures and pressures with the mostsignificant increase believed to be in localized pressures. The increasein pressures and temperatures within the high shear device areinstantaneous and localized and quickly revert back to bulk or averagesystem conditions once exiting the high shear device. In some cases, thehigh shear mixing device induces cavitation of sufficient intensity todissociate one or more of the reactants into free radicals, which mayintensify a chemical reaction or allow a reaction to take place at lessstringent conditions than might otherwise be required. Cavitation mayalso increase rates of transport processes by producing local turbulenceand liquid micro-circulation (acoustic streaming). An overview of theapplication of cavitation phenomenon in chemical/physical processingapplications is provided by Gogate et al., “Cavitation: A technology onthe horizon,” Current Science 91 (No. 1): 35-46 (2006). The high shearmixing device of certain embodiments of the present system and methodsis operated under what are believed to be cavitation conditionseffective to dissociate the benzene into free radicals exposed tochlorination catalysts for the formation of the chlorobenzene product.

Description of High Shear Chlorobenzene Production Process and System

The high shear chlorobenzene production process and system of thepresent disclosure will now be described in relation to FIG. 2 which isa representative process flow diagram of a high shear system (HSS) 100for the production of chlorobenzene from benzene and chlorine gas. FIG.2 illustrates the basic components of a representative high shearchlorobenzene production system. These components comprise pump 5, highshear mixer 40, and reactor 10.

Pump 5 is used to provide a controlled flow throughout high shear device(HSD) 40 and high shear system 100 for chlorobenzene production. Pumpinlet stream 21 comprises liquid benzene for introduction to pump 5. Incertain embodiments, pump inlet stream 21 comprises dry benzene. Pump 5increases the pressure of the pump inlet stream 21 to greater than about203 kPa (about 2 atm); alternatively, the inlet stream 21 is pressurizedto greater than about 304 kPa (about 3 atm). Additionally, pump 5 maybuild pressure throughout HSS 100. In this way, HSS 100 combines highshear with pressure to enhance reactant intimate mixing. Preferably, allcontact parts of pump 5 are stainless steel, for example, 316 stainlesssteel. Pump 5 may be any suitable pump, for example, a Dayton PressureBooster Pump Model 2P372E, Dayton Electric Co (Niles, Ill.).

The pressurized benzene liquid exits pump 5 via pump exit stream 12.Pump exit stream 12 is in fluid communication with HSD inlet stream 13.In certain instances, dispersible gas stream 22 comprising chlorine gasis introduced or injected to HSD inlet stream 13. In some embodimentschlorine gas may continuously be fed into exit stream 12 to form HSDinlet stream 13. HSD inlet stream 13 comprises a mixture of chlorine gasand catalyst in liquid benzene. Dispersible gas stream 22 andpressurized pump exit stream 12 may be injected separately into HSDinlet stream 13 for processing by high shear device 40. Furthermore, anysuitable chlorination catalyst known to those of skill in the art may beintroduced into HSD inlet stream 13 for processing by HSD 40. In certaininstances, the catalyst introduced comprises a Lewis acid catalyst. Thecatalyst may be chosen from metallic chlorides and iodine. Inembodiments, the catalyst is selected from Lewis acids selected from thegroup consisting of Fe, FeCl₃, and AlCl₃. HSD inlet stream 13 is influid communication with the high shear device 40.

HSD 40 serves to intimately mix the liquid benzene solution withdispersible gas stream 22 and the catalyst. As discussed in detailabove, high shear device 40 is a mechanical device that utilizes, forexample, a stator rotor mixing head with a fixed gap between the statorand rotor. In high shear device 40, chlorine gas and benzene are mixedto form an emulsion comprising microbubbles and nanobubbles of chlorinegas. In embodiments, the resultant dispersion comprises bubbles in thesubmicron size. In embodiments, the resultant dispersion has an averagebubble size less than about 1.5 μm. In embodiments, the mean bubble sizeis less than from about 0.1 μm to about 1.5 μm. Not to be limited by aspecific method, it is known in emulsion chemistry that submicronparticles dispersed in a liquid undergo movement primarily throughBrownian motion effects. Thus it is believed that submicron gasparticles created by the high shear device 40 have greater mobilitythrough boundary layers of solid catalyst particles thereby facilitatingand accelerating the catalytic reaction through greater transport ofreactants. In embodiments, the high shear mixing produces gas bubblescapable of remaining dispersed at atmospheric pressure for about 15minutes or longer depending on the bubble size. In embodiments, the meanbubble size is less than about 400 nm; more preferably, less than about100 nm. HSD 40 serves to create an emulsion of chlorine bubbles withinhigh shear inlet stream 13 comprising aqueous aldehydes and chlorinegas. The emulsion may further comprise a micro-foam.

The emulsion exits HSD 40 by the HSD emulsion stream 18. The HSDemulsion stream 18 may undergo further processing prior introduction tothe reactor 10. Before introduction to reactor 10, the moisture contentof benzene may be reduced. In certain embodiments, the benzene in HSDemulsion stream 18 comprises dry benzene. HSD emulsion stream 18 isintroduced into reactor 10 by reactor inlet stream 19. Reactor inletstream 19 is in fluid communication with reactor 10.

Forming the emulsion in the presence of a catalyst may initiate thereaction process of chlorination. Chlorination reactions will occurwhenever suitable time temperature and pressure conditions exist. Ininstances where a slurry based catalyst is utilized, reaction is morelikely to occur at points outside reactor 10. In this sense chlorinationcould occur at any point in the flow diagram of FIG. 2 where temperatureand pressure conditions are suitable for the reaction. Nonetheless adiscrete reactor 10 is often desirable to allow for increased residencetime, agitation and heating and/or cooling. In fixed bed catalystapplications, the catalyst increases the rate of the chlorinationreaction.

Reactor 10 is configured for chlorobenzene production. Reactor 10 mayfurther comprise temperature control (i.e. heat exchanger), stirringsystem, and level regulator as known to those of skill in the art. Inembodiments, inlet stream 15 is fluidly coupled to the reactor 10. Inletstream 15 may comprise additional catalyst for catalyzing thechlorination of benzene to chlorobenzene. As described herein, a Lewisacid may be added to promote the production of chlorobenzene. In certainembodiments, in the reactor 10, chlorine gas in reacts with dry benzeneutilizing a Lewis acid catalyst at a predetermined temperature to yieldchlorobenzene mixtures. In embodiments, chlorobenzene production iscontinuous within the reactor. The reactor 10 is drained by productstream 16.

A specified reaction temperature may be maintained in the reactor 10, asknown to those of skill in the art. In certain embodiments, the reactorincludes internally or externally positioned heat exchangers.Alternatively, heat exchangers may be positioned in any location alongthe production stream within HSS 100. Suitable locations for externalheat transfer devices include between the pump 5 and the high shearmixer 40, between the high shear mixer 40 and the reactor 10, andbetween the reactor and further processing systems. There are many typesof heat transfer devices that may be suitable; such exchangers mightinclude shell and tube, plate, and coil heat exchangers withoutlimitation. Further heat exchangers may be known to one skilled in theart.

The chlorination product stream 16 comprises chlorobenzene, unconvertedbenzene, and HCl. Product stream 16 may be treated by any means known inthe art to recover any unreacted benzene, remove produced HCl, andpurify chlorinated benzene. In an embodiment illustrated in FIG. 2,product stream 16 is fluidly coupled a treatment system 99. Treatmentsystem 99 comprises treatment vessel 30; the treatment vessel 30 isfluidly coupled to reactor 10 by product stream 16. Further, thetreatment vessel 30 is drained by catalyst free stream 32 to a holdingtank 50. Holding tank 50 stores the catalyst free chlorobenzene productprior to further treatment. In the illustrated embodiment, holding tank50 is in fluid communication with a chlorobenzene distillation column(s)60 via distillation inlet stream 33. The chlorobenzene distillationcolumn(s) 60 are in fluid connection with further processing streams 80by the chlorobenzene stream 65. Chlorobenzene distillation column(s) 60may be further in communication with a reflux drum 90, by gas recyclesystem 62. Gas recycle system 62 is fluid communication between refluxdrum 90 and chlorobenzene distillation column(s) 60. In certaininstances, reflux drum 90 is in fluidly coupled to treatment vessel 30by water stream 92. Reflux drum 90 additionally comprises recoveredbenzene stream 95 in fluid communication with secondary distillationcolumn(s) 70. Secondary distillation column(s) 70 may drain benzeneholding tank 130 via stream 71 to feed recycle stream 20. Recycle stream20 is fluidly coupled to pump inlet stream 21.

Treatment vessel 30 comprises a tank, vessel, or container configuredfor acid and catalyst removal. In embodiments, the acid and catalystfrom product stream are removed with water before introduction toholding tank 50. The products comprising chlorobenzene from holding tank50 are fed into chlorobenzene distillation column(s) 60. Chlorobenzenestream 65 is removed for further processing into final products such asrubber, dyes, pesticides, and the like, without limitation.Alternatively, Chlorobenzene stream 65 may be sent for furtherseparation, for example to a distillation column whereinmonochlorobenzene may be separated from other chlorobenzene isomers,such as paradichlorobenzene, orthodichlorobenzene, and trichlorobenzene.

In certain embodiments, treatment vessel 30 is in fluid communicationwith solvent recovery system 110. Water is drained from treatment vessel30, with dissolved acids and catalyst, and is sent via stream 105 to thesolvent recovery system 110 for further removal of the organics from thewater.

Benzene-containing vapor in the gas recycle system 62 is directed fromdistillation column 60, condensed, and sent to reflux drum 90. Inembodiments, a portion of benzene from reflux drum 90 is recycled todistillation column(s) 60 by gas recycle system 62. Water stream 92 maybe removed from reflux drum 90 for return to treatment vessel 30 and/orcontinuing processing by solvent recovery system 110. A portion ofrecovered benzene stream 95, from reflux drum 90, may be supplemented bywet benzene from holding tank 130. The stream 71 is sent to secondarydistillation column(s) 70 with recovered benzene stream 95 to producedry benzene. The dry benzene makes up recycle stream 20, and may beinjected into pump inlet stream 21 for recycling through the high shearsystem, comprising the high shear device 40.

In embodiments, use of the disclosed process comprising reactant mixingvia high shear device 40 allows greater conversion of benzene tochlorobenzene and/or an increase in throughput. In embodiments, theremay be several high shear devices 40 used in series. In embodiments, themethod comprises incorporating high shear device 40 into an establishedprocess thereby enabling the increase in production (greater throughput)from a process operated without high shear device 40. The superiordissolution provided by the high shear mixing may allow improvements inoperating conditions such as temperature, pressure, and contact timewhile maintaining, or increasing, reaction rate. In embodiments, themethod and system of this disclosure enable design of a smaller and/orless capital intensive process than previously possible without theincorporation of external high shear mixer 40. In embodiments, thedisclosed method reduces operating costs/increases production from anexisting process. Alternatively, the disclosed method may reduce capitalcosts for the design of new processes. Potential benefits of thismodified system and method for the production of chlorobenzene include,but are not limited to, faster cycle times, increased throughput,reduced operating costs, and/or reduced capital expense due to thepossibility of designing smaller reactors and/or operating thechlorobenzene production at lower temperature and/or pressure.

While preferred embodiments of the invention have been shown anddescribed, modifications thereof can be made by one skilled in the artwithout departing from the spirit and teachings of the invention. Theembodiments described herein are exemplary only, and are not intended tobe limiting. Many variations and modifications of the inventiondisclosed herein are possible and are within the scope of the invention.Where numerical ranges or limitations are expressly stated, such expressranges or limitations should be understood to include iterative rangesor limitations of like magnitude falling within the expressly statedranges or limitations (e.g., from about 1 to about 10 includes, 2, 3, 4,etc.; greater than 0.10 includes 0.11, 0.12, 0.13, and so forth). Use ofthe term “optionally” with respect to any element of a claim is intendedto mean that the subject element is required, or alternatively, is notrequired. Both alternatives are intended to be within the scope of theclaim. Use of broader terms such as comprises, includes, having, etc.should be understood to provide support for narrower terms such asconsisting of, consisting essentially of, comprised substantially of,and the like.

Accordingly, the scope of protection is not limited by the descriptionset out above but is only limited by the claims which follow, that scopeincluding all equivalents of the subject matter of the claims. Each andevery claim is incorporated into the specification as an embodiment ofthe present invention. Thus, the claims are a further description andare an addition to the preferred embodiments of the present invention.The discussion of a reference in the Description of Related Art is notan admission that it is prior art to the present invention, especiallyany reference that may have a publication date after the priority dateof this application. The disclosures of all patents, patentapplications, and publications cited herein are hereby incorporated byreference, to the extent they provide exemplary, procedural or otherdetails supplementary to those set forth herein.

1. A method for producing chlorobenzene, comprising: obtaining a highshear device having at least one rotor/stator set configured forproducing a tip speed of at least 5 m/s, wherein the high shear devicecomprises at least one rotor and at least on stator; forming an emulsionof benzene and chlorine gas; wherein said benzene comprises apressurized liquid solution, and said chlorine gas comprises bubbles inthe emulsion with a mean diameter of less than about 5 μm; introducingsaid emulsion into a reactor comprising a catalyst; and reacting saidemulsion at a temperature less than about 40° C. in said reactor, fromwhich a product comprising chlorobenzene is removed.
 2. The method ofclaim 1 said pressurized benzene solution is pressurized to least about203 kPa.
 3. The method of claim 1 wherein said chlorine gas bubbles havean average diameter of less than about 1.5 μm.
 4. The method of claim 1wherein said high shear device has a tip speed of at least about 5 m/s.5. The method of claim 4 wherein said high shear device produces alocalized pressure of about 1000 MPa at the tip.
 6. The method of claim1 wherein forming said emulsion comprises subjecting said oxidant gasbubbles and pressurized aqueous solution to a shear rate of greater thanabout 20,000 s⁻¹.
 7. The method of claim 1 wherein forming said emulsioncomprises an energy expenditure of at least 1000 W/m³.
 8. The method ofclaim 1 wherein the emulsion comprises a micro-foam.
 9. The method ofclaim 1 wherein the catalyst comprises one chosen from the groupconsisting of Lewis acids, metallic chlorides, iodine, or combinationsthereof.
 10. The method of claim 1, further comprising treating theproduct with hydrochloric acid.
 11. The method of claim 10, furthercomprising distilling the product at least once to remove thechlorobenzene.
 12. A method for producing chlorobenzene, the methodcomprising: forming an emulsion of chlorine gas bubbles in aqueoussolution comprising benzene by introducing liquid benzene and chlorinegas into a high shear device and subjecting the mixture of liquidbenzene and chlorine gas to a shear rate of at least 20,000 s⁻¹.
 13. Themethod of claim 12 wherein the high shear device comprises at least onerotor and at least one stator.
 14. A system for the production ofchlorobenzene, the system comprising; a pump positioned upstream of adispersible chlorine gas inlet; a high shear device which produces anemulsion of chlorine gas in an aqueous solution, the dispersion havingan average bubble diameter of less than about 5 μm; and a reactormaintained at a temperature of less than about 40° C. for thechlorination reaction of benzene to chlorobenzene; the reactor fluidlyconnected to the outlet of the high shear device.
 15. The system ofclaim 14 wherein the high shear device is configured to produce anemulsion.
 16. The system of claim 14 wherein the high shear devicecomprises a tip speed of at least about 5 m/sec.
 17. The system of claim14 wherein said high shear device produces a localized pressure of atleast about 1000 MPa at the tip.
 18. The system of claim 14 wherein saidhigh shear device subjects said oxidant gas bubbles and pressurizedaqueous solution to a shear rate of greater than about 20,000 s⁻¹. 19.The system of claim 14 wherein said high shear device comprises anenergy expenditure of at least 1000 W/m³.
 20. The system of claim 14wherein said high shear feed stream comprises a micro-foam.